Selective signaling circuits for carrier systems



March 23 1926a R.K.BONELL SELECTIVE SIGNALING cmcums FOR CARRIER SYSTEMSFiled May 15. 1924 2 Sheets-Sheet 1 INYEN TOR J A ORNE Y March 23,1926.1,577,515

R. K. BONELL.

SELECTIVE SIGNALING CIRCUITS FOR CARRIER SYSTEMS Filed May 15, 1924 2Sheets-Sheet 2 Carrier fies. 1/ I a wuww (may Z x 2 m Relay W 1/ 3,322 24 IN VEN TOR 6 A TTORNE Y Patented Niar. 23, 1926.

UNETED STATES PATENT oFFic RALPH. K. BONELL, OF EAST ORANGE, NEW JERSEY,ASSIGNOR T0 AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OFNEW YORK.

SELECTIVE SIGNALING CIRCUITS FOR CARRIER SYSTEMS.

Application filed May 15,

T 0 all whom it may concern:

Be it known that I, RALPH K. BoNELL, a citizen of the United States,residing at East Orange, in the county of Essex and State of New Jersey,have invented certain Improvements in Selective SignalingGircuits forCarrier Systems, of which the following is a specification.

This invention relates to transmission circuits and more particularly toarrangements for transmitting ringing or other supervisory signals inconnection with transmission circuitsl v One of the objects of theinvention is to provide a signaling arrangement whereby a D group oftransmission channels may have.

associated therewith a signaling apparatus commonto the group fortransmitting ringing or other supervisory signals. The severaltransmission channels may comprise a plurality of separate wire lines orother transmission paths or they may comprise the multiplex channels ofa multiplex system in which a plurality of signaling paths aresuperposed on the same circuit.

Another object of the invention is to pr vide a common signalingarrangement of the type above referred to, in'which the signalsoriginating with a plurality of channels will be stored up andtransmitted successively over a common signaling path. The commonsignaling path may be either a separate wire circuit or it may be achannel of the multiplex system set aside for this purpose.

Another object of the invention is to provide a system of the type abovedescribed, in which the receiving mechanism of the signalingapparatuswill be so arranged as to identify supervisory or other signalsoriginating with difi'erent channels and will properly allocate thereceived signals to the proper terminal conductors.

Other and further objects of the invention will be clear from thefollowing description when read in connection with the accompanyingdrawing, Figures 1 and 2 of which illustrate circuit diagrams embodyingtwo forms of the invention. a

Referring to Fig. 1 LIL designates a transmission line, such as atelephone line, which is multiplexed in a well known manner so that itmay be associated with a plurality of terminal lines, such as L L L andL,

1924. Serial No. 713,583.

for the simultaneous transmission of telephone conversations. In orderto interconnect the main transmission line ML with the terminal lines,each terminal line is associated through the hybrid coils and balancingnetworks such as N N N and N with a transmitting carrier channel and areceiving carrier channel. For example, the line L is associated withthe transmitting carrier channel TL including suitable carriertransmitting apparatus M Likewise, the line L is associated with thecarrier receiv ing channel RL including the carrier receiving apparatusschematically indicated at The carrier apparatus is of a type. wellknown in the art and is not shown in detail. The various transmittingchannels are connected through filters, such as TF to TF inclusive, to acommon circuit TL, which is associated with the main line ML. Similarly,the various receiving carrier channels are connected through filters RF,to RF inclusive with a common circuit RL associated with the main lineML;

The signaling apparatus associated with the group of lines L to Linclusive comprises a set of ringing. responsive relays 11, 12, 13 and14, individual-to. the line. A signal storing circuit is also providedwhich is common to the four lines shown, the signal storing circuitincluding storing relays 31 to 34 inclusive, controlled by the ringingresponsive relays 11 to 14: inclusive. Also four additional relays 41 to44 inclusive are provided inconnection with the storing circuit, theserelays being so arranged that when one. is operated it controls thetransmission of a signal originated by one of the corresponding terminallines and at the same time prevents the other corresponding relays frombeing operated until the signal of the line having control istransmitted.

A code transmitting apparatus is associated with the signal storingcircuit, said transmittig apparatus comprising a transmitting motor TM,driving a shaft upon which a plurality of cams 71 to 74 inclusive areprovided, the cams being arranged to transmit code signalscharacteristic of the several linesL to L inclusive. A fifth cam 70 isalso provided for performing certain translating operations inconnection with the storing circuit. Switches are controlled by thevarious cams, which operate to transmit code groups of alternating Wavesto a suitable modulator M tube 0 is also associated with the modulatorto impress thereon a carrier frequency to be used in the transmission ofsignals from the several terminal lines. The modulator operates tomodulate the carrier frequency thus supplied, in accordance with codegroups of alternating waves of some suitable ringing frequency such as,for example, cycles, and the modulated carrier is then transmittedthrough a suitable filter Ti to the line ML.

The receiving apparatus of the signaling arrangement comprises areceiving lilter RF for select ng out the modulated carrier frequencyupon which the signals transmitted from the distant station aresuperposed, and a suitable detector D for detecting from the carrier thegroups of 135 cycle waves making up the code signals. The detected lowfrequency waves operate a suitable alternating current. may 110. Thisrelay operates to close a circuit each time a group of 135 cycle wavesis transmitted by the detector. In this manner, direct current codepulses are transmitted to a relay 111, which controls a suitableselecting arrangement, whose operation is determined by the codereceived.

This selecting arrangement comprises a series of escapement relaysarranged in pairs, the first pair being designated 51 and 51.respectively, the second pair being designated 52 and 52 respectively,etc. Only 'one relay of the last pair of escapement relays is provided,this relay being designated 54. The pairs of escapement relays are soarranged that one relay of a pair is operated when the relay 111 isenergized and the other relay of the pair is operated when the relay 111is deenergized, and each succeeding relay in the series of escapementrelavs is so arranged that it can not be operated until the precedingrelay in the series has been energized.

A series of four selecting relays 61 to 64 inclusive are associated withthe escapement relays, the selecting relays being individua lyresponsive to a. different code under the control of the escapementrelays. The selccting relays are individual to the four terminal linesL, to L, inclusive and operate to transmit ringing signals to theterminal line selected under the control of a suitable timing apparatus.

The timing apparatus comprises a timing motor RM. driving a shaft havingthereupon a series of cams 81 to 84 inclusive, one individual to eachterminal line, and a fifth can! PM. The cam of the group 81 to 84inclusive individual to a particular line initiates the ringing signalfor that line. while the cam 9. operates to terminate the ringingaigna'; initiated upon any line.

An oscillating- Further details of the invention will be clear from adetailed description of the operation which is as follows: Let us assumethat a ringing signal comes in from the terminal line L and that amoment thereafter another signalcomes in from the terminal line L thelater signal arriving before the signal coming in from the line L hashad an opportunity to be transmitted. The ringing signal coming in fromthe line L Will operate the ringing responsive relay 12, which in turnopens the circuit of the nor mally operated relay 22 to .close thecircuit of the storing relay 32. The ringing sig nal incoming from theline L,, which arrives a moment later, in turn operates the ringingresponsive relay 14, which opens the normally closed circuit of, therelay 24, thereby completing a circuit from ground, through the windingof the storing relay 34. The storing relay 32, upon being operated, islocked up over its lefthand front contact and the right-hand backcontact of relay 102. Similarly, relay 34 is locked up over its lefthandfront contact and the right-hand back contact of relay 104.

At its right-hand front contact relay 32 closes a circuit for the relay42, from battery. over the normally closed contact controlled by cam 70,over the inner right-hand contact of relay 44, over the inner right-handcontact of relay 43, through the winding of relay 4.2, over theright-hand front contact of relay 32 and over the inner left-handcontact of relay 41 to ground. Relay 42, upon being energized, at itsinner lefthand contact opens the ground connections to the windings ofthe relays 43 and 44, thereby preventing the circuit of the relay 44from being closed by the relay 34. At; its inner right-hand cont-act,relay 42 opens the battery connection from the relay 41 to the camswitch controlled by cam 70. Consequently, it will be apparent that whenone of the reays 41 to 44 inclusive is operated all of the other relays'of the group are prevented from being actuated.

At its outer left-hand contact, relay 42 completes a circuit frontground. through the winding of relay 112. Relay 112 in turn closes acircuit of the motor TM and starts the cams to 74 inclusive revolving.Relay 42 at its right-hand outer contact closes a circuit of relay 102.The latter relay, at

its left-hand front contact, completes a looking circuit for the relay42, independently of the storing relay 32. At its right-hand backcontact relay 102 opens the looking circuit of the storing reiay 32 andreleases the storing relay, while at its right-hand front contact saidrelay 102 completes a circuit to the switches controlled by cam 72.lVhile the operations above described and the operations about to bedescribed take place, the

loo

Ill)

storing relay 34 remains locked up because the relay 104 can not beactuated to release the relay 34 until the relay 44 is operated.

As the motor TM revolves the cam shaft, 6 the cam 72 successively closesand opens the switch controlled thereby, to transmit a series of closedand open circuit pulses to the relay 113. This particular cam isarranged to transmit one short closed circuit pulse and one long closedcircuit pulse. Each time the relay 113 is energized by a long or shortclosed circuit pulse a group of carrier waves, having a frequency of 135cycles, is transmitted to the modulator M and modulates the carrierfrequency from the oscillator O to transmit a modulated code signal overthe line 11%.

As the shaft of the motor TM completes one revolution, the fifth cam 70operates to open the normally closed switch controlled thereby to removebattery from the circuit of relay 42, thereby releasing said relay.Relay 42, upon being deenergized, opens the circuit of relay 102, whichin turn opens the locking circuit of relay 42 and also opens the circuitcontrolled by the cam 72. Relay 42, upon being deenergized, also opensthe circuit of the relay 112 so that the motor TM will come to rest.

30 At its inner right-hand back contact relay 42 completes a circuit forthe relay 44 under the control of the storing relay 34 as follows: frombattery, over the switch controlled by cam 70, through the winding ofthe relay 44, right-hand front contact of relay 34, and over theleft-hand inner back contacts of relays 43, 42 and 41 in-series, toground. Relay 44, at its left-hand front contact, closes a circuit forthe relay 112 to again set the.

motor TM into operation, and at its inner right hand contact disablesrelays, 43, 42 and 41. At its outer right-hand contact relay 44 close acircuit of relay 104. The latter relay operates to lock up relay 44 andunlock the 45 )storing relay 34, so that the latter isrestored .tonormal. Relay 104, at its right-hand front contact, closes a circuit forthe switch operated by. the cam 74. The cam 74 now proceeds totransmit-a code combination consisting of three short closed circuitpulses and ,one long closed circuit pulse. This causes a correspondinggroup modulation of the carrier supplied ,by the oscillator O totransmit the signal corresponding to the line L, over the main line mi.7

In order to understand the operation of the receiving apparatus at thedistant-end of the main line, the operation of the receiving apparatusillustrated, in response to similar signals transmitted over the mainline from the distant station, will be described. Let us suppose that acarrier current is being received which is modulated by 135 cyclecurrent, broken upinto groups corresponding to one short closed circuitits inner lower contact rela pulse followed by one long closed circuitpulse. This carrier current will be selected from other carrierfrequencies by the filter RF and impressed upon the detector D, so thatthe detector D will operate to detect alternating current of 135 cyclefrequency broken up to correspond to one short closed circuit pulsefollowed by one long closed circuit pulse. The alternating relay 110will be energized to attract its armature once for each group.

In response to the first group, relay 110. will close the circuit ofrelay 111, which in turn attracts its armature and completes the circuitof escapement relay 51. Relay 51, at its inner upper contact, completesa locking circuit for its own winding, over the back contact of relay114 and at its upper outer contact prepares the circuit of the secondescapement relay 51. It will be observed that relay 115 is normallyenergized and that a circuit is completed over the lower back contact ofrelay 111. The opening of this contact in response to short pulses ofcurrent through relay 111 does not a permit the relay'1l5 to release itsarmatures, as it is a slow-release relay,-and this relay will not bereleased until a long pulse is received, as will be described later.Consequently, the circuit, which will be closed through the upperwinding of selecting relay .61 over the lower front contact of relay 51,is held open at the upper contact of the slow-release relay 115, and therelay 61 is not actuated at this time. At the end of the first shortpulse, relay 111 is released by the armature of relay 110 and thecircuit is closed over the lower back contact of relay 111 and over theouter upper contact of relay 51, through the winding of escapcment relay51. The latter relay is energized and locked up over its upper innercontact to round, over the back contact of relay 114. elay 51 at itsouter upper contact, prepares the circuit of escapement relay 52.

hen the following long group is detected by the detector D relay 110transmits a lon pulse to relay 111, which is energized and completes acircuit from ground, over its front contact, and over the outer uppercontact of escapement relay 51, to esca-pement relay 52. The latterrelay is locked up over its inner upper contact and at its outer uppercontact prepares a circuit for escapement relay 52'. At its outer lowercontact, relay 52 holds open the circuit of selecting relay 61 so thatthis relay cannot now be energized. At 52 prepares a circuit through theupper wlnding of selecting relay 62.

The long pulse which energized relay 111, as just described, held openthe circuit of the slow-release relay for a suhicient length of time topermit it to release. As

soon as this relayreleases a circuit is closed 3 of selecting relay 62,and over the outer lower contacts 01'' eseapement relays 53 and 54 inseries, to battery. The upper and lower armatnres of relay 62 are soarranged that when attracted they press the upper and lower middlecontacts 01' said relay into contact with the upper and lower innercontacts of said r'elay. A locking circuit is accordingly establishedfor the relay 62, from battery, through its lower winding, over itslower armature and lower middle contact, and over the outer lowercontact of relay 92, to ground. At the same time a circuit is completedfrom battery, over the lower contact of deenergized relay 115, throughthe winding of relay 1l-l-, over the inner lower and lower middlecontacts of relay 62, and over the outer lower back contact ot'v relay92 to ground. Relay 114-, upon being energized, at its lower contactdisconnects ground from the locking circuits of the several eseapementrelays which have been energized, thus restoring them to normal.

Relay 62 completes a circuit over its upper middle contact and upperarmature through the winding of relay 116 to battery. Relay 116 is atonce loci-:ed up over its lower contact and over the contacts controlledby cam 80. At its upper contact relay 116 completes a circuit for thetiming motor RM, which begins to rotate the cams to 84 inclusive. Acircuit is also completed by the relay 62, over its upper middle andupper inner contacts to the switches controlled by the cam 82. Shortlyafter the beginning of the rotation of the cam shaft, the cam 82 permitsterminal line L,. At its lower outer contact relay 92 disconnects groundfrom the lower middle contact of relay 62, thereby opening the circuitof relay 1 14, and the locking circuit of relay 62, restoring theserelays to normal. All of the circuits of the various escapement relaysand the circuits of the selecting relays 61 to 64 inclusive are now innormal condition so that the selection in response to the next codecombination may take place while the ringing signal is being transmittedto the line L, under the. control of the timing motor RM.

As the shaft controlled by the timing motor RM continues to rotate,ringing current is continuously transmitted to the line L by locked uprelay 92 until just before the cam shaft has completed one revolution,

at which time the tooth upon cam 80 engages the switches controlled bythe cam to dis connect ground from the locking circuit of relay 92 andfrom the locking circuit of 116. Relays 92 and 116 are accordinglydeenergized, the former disconnecting ringing current from the line Land the latter opening the circuit of the timing motor RM to stop therotation of the cam shaft.

'hile the ringing signal is being transmitted to the line L another codecombination may be received from the main line ML. Let us suppose that acarrier current is now being received, which is modulated by 135 cyclewaves broken up into groups corresponding to three short pulses and onelong pulse. The groups of 135 cycle Waves will be detectedby thedetector D and the alternating current relay 110 will transmit threeshort pulses and one long pulse to the relay 111. The latter relay, inresponse to the first pulse, energizes and locks up eseapement relay 51.At the end of the pulse, eseapement relay 51 is energized. In responseto the second pulse, relay 111 energizes and locks up eseapement relay52, and at the end of this pulse relay 52' is energized and locked up.Similarly, eseapement relays 53 and 53 are energized and locked up atthe beginning and ending respectively of the third pulse. At thebeginning of the linal long pulse through the relay 111, the lasteseapement relay 54 is energized and locked up.

It will be observed that each eseapement relay, such as 51, 52, 53 and54, prepares a circuit for the corresponding selecting relay of thegroup 61 to 64 inclusive. As the first eseapement relay of eachsucceeding pair is energized, however, it looks up and holds open thecircuit of the selecting relay prepared by the first escapement relay ofthe preceding pair. For example, escapement relay 51 prepares thecircuit of selecting relay 61. the circuit of relay 61 and prepares thecircuit of selecting relay 62. Relay in turn, however, holds open thecircuit of relay 62 at its outer lower contact and prepares the circuitof escapement relay 63 at its lower inner contact. Finally, eseapementrelay 54 holds open the circuit of selecting relay 63 at its outer lowercontact and at its inner lower contact prepares the circuit through theupper winding of eseapement relay 64. Consequently, in response to thecode group just received, selecting relays 61, 62 and 63 are disabled.

During the continuance of the long pulse received by the relay 111, thecircuit of slowrelease relay 11.5 is held open so that this Relayhowever holds 0 )en till relay releases its armatures and completes acircuit from ground, over its upper back contact, and over the innerlower contacts of escapement relays 51, 52 and 53 in series, and

thence over the inner lower contact of es-' capement relay 54 throughthe upper winding of selecting relay 64 to battery. Relay 64 isenergized and attracts its armatures to control its contact in a mannersimilar to that described in connection with the relay 62.

Relay 64, upon being energized, is locked upthrough its lower windingand over its lower armature and lower middle contact to ground, over theouter lower back contact ofrelay 94. At the same time,-relay 1.14 isenergized by a circuit completed from battery, over the lower backcontact of relay 115, through the winding of relay 114, over the innerand middle lower contacts of relay 64, and over the lower outer backcontact of relay 94 to ground; Relay 114 operates to release all of theescapement relays and restore them to normal.

Relay 64, which is now locked up, completes a circuit from ground, overits upper armature, and through the winding of relay 116 to energizeandlock up the latter relay,

thereby setting the timing motor RM into operation. Shortly after theshaft begins to rotatethe cam 84 permits the switch con-. tactscontrolled thereby to close and establish a momentary circuit for therelay 94, which circuit may be traced from ground, over the middle andinner upper contacts of relay 64, over the switches controlled by thecam 84, and through the winding of relay 94 to battery. Relay 94 is atonce energized and locked up' over its outer upper contact and over theswitch controlled by cam 80. Ringing current is applied to the terminalline ll, over the inner contacts of the relay 94. At the same time,relay 94, at its outer lower contact, disconnects ground from the lowermiddle contact of relay 64, thereby opening the locking circuit of thelatter relay and also opening the circuit of relay 114. Relays 64 and114 are restored to normal and relay 111 having been released at the-endof the long impulse, with the consequent energization of slowreleaserelay 115, all of the escapement and selecting relays are in theirnormal condition ready to' respond to the next received code group.

In the meantime, as the shaft of the t1m-.

' tor RM and stops the cam shaft.

A modified arrangement is shown in Fig. 2, this particular arrangementdiffering from that already described principally in the fact thatinstead of relay selective apparatus for receiving the signalsstep-bystep selectors are employed, these selectors being of the generaltype disclosed in U. S. patent to Field, 1,343,256, of June 15, 1920.Thecircuit of Fig. 2 also differs from that of Fig. 1 in that the timingarrangement for controlling the transmission of the ringing signal tothe terminal lines comprises a chain of relays instead of a motor-drivencam control.

The details of-the apparatus shown in Fig. 2 may be fully understoodfrom the description of the operation. In describing the operation. itwillbe unnecessary to refer to the transmitting apparatus or theoperation thereof since the transmittingap,- paratus is identical withthat shown in Fig. 1 and operates in the same manner. It should benoted, however, that because of the particular setting of thestep-by-step' selectors employed, each of the transmitting cams 71 to 74inclusive is arranged to transmit one additional short pulse. ple, thecam 71 transmits one short pulse and one long pulse, whereas thecorresponding cam of Fig. 1 transmits only the long pulse. Likewise, cam7 4 in Fig. 2 transmits four short pulses and a long pulse, whereas thesame cam in Fig. 1 transmits three short pulses and one long pulse. Theextra pulse is'not essential to the arrangement shown in Fig. 2,however, as this pulse may be omitted by changing the normal setting ofthe selectors. For example, the selector wheel S is so set that it. isadvanced three steps to effect selection, one step being taken at thebeginning of a short pulse, a second step being taken at the end of thepulse, and a third step being taken at the beginning leased at the endof the long pulse. Ifthe For exam- Ill) selector were set to select atthe end of the first step it would takd this step at thebeginning of onelong pulse and would then be restored at the end of the long pulse, sothat the extra tooth would not be necessary on the correspondingtransmitting cam.

The receiving operation is as follows: Let

us assume that a combination is being transmitted from the distantstation for the purpose of sending a ringing signal over the will befollowed by one for the purpose of transmitting a ringin signal over theterminal line L,. The rst code combination will, in accordance with thetransmittin cams shown, comprise two short pulses and one long pulse.Consequently, the carrier frequency transmitted from the distant stationwill be modulated in accordance with 135,,cycle waves broken up intogroups oonchannel L and that this code combination sisting of two shortgroups and one -long group. The detector D will detect the groups of 135cycle alternating current and impress them upon the alternating currentrelay 110, which is arranged to close its con tact 117 at the beginningof each group and hold it closed until the end of each group of waves,thus transmitting to the relay 118 rect current combinations consistingof a series of short pulses followed by a long pulse, depending upon the.particular code combination received. Each time a current pulse istransmitted through the relay 118 it attracts its armature and charges acondenser 119 so that a brief surge of current flows through each of themagnets P to P inclusive of the selectors in one direction. When therelay 118 releases its armature at the end of a given pulse, thecondenser 119 is connected to ground, and by the discharge of thecondenser a surge of current flows in the opposite direction througheach of the magnets P to P inclusive. Each of the polar magnets P to I"inclusive thus receives alternate positive and negative impulses.

Each polar magnet controls apparatus (not disclosed but fully set forthin the patent to Field, already referred to) whereby the correspondingdisc of the group of discs S to S inclusive is stepped forward one stepfor each positive impulse, and one step for each negative impulse,regardless of the length of the pulse actuating the relay 118. Thearmature of each polar magnet has a normal neutral position and when thearmature is in the neutral position the disc will be free to return toits normal position under the influence of a spring (not shown) unlessthe disc is maintained in the position to which it has been stepped bythe engagement of a latch, such as 121, with a pin, such as 131, locatedupon the periphery of the disc. The pin on each disc is arranged toengage the latch at a different point in its revolution and when thelatch engages the pin a wiper, such as 141, closes a contact to actuatea signaling relay.

When the relay 118 attracts its armature at the beginning of the firstshort pulse, each of the polar magnets P to P inclusive advance each ofthe selector wheels S to S, inclusive in a clockwise direction one step.Since the pulse is a short pulse the relay 118 releases its armaturebefore the armatures of the polar magnets have had an opportnnity toshift to their neutral positions and free the selector wheels.Consequently, the discharge of the condenser 119, which occurs whenrelay 118 is released, causes a surge of current in the oppositedirection through each of the polar magnets, thus throwing the armatureof each magnet in the opposite direction and advancing each of theselector wheels a second step. The succeeding short pulse through therelay 118 follows the preceding pulse so quickly that the armatures ofthe polar magnets are not permitted to shift to their neutral positions,and when the relay 118 attracts its armature the arms-- tures of thepolar magnets are shifted to advanceeach selector wheel a third step. Atthe end of the pulse, the relay 118 releases its armature and the polarmagnets advance each selector wheel a fourth step. As the selector wheelS passed through the fourth step its wiper 141 momentarily closed acircuit through the relay 91 but the momentary closing of said circuitwas not suflicient to energize the relay 91.

Upon receiving the succeeding long pulse relay 118 again attracts itsarmature and charges the condenser 119 so that a surge of current flowsthrough each of the polar magnets, thus advancing each of the selectorwheels a fifth step and permitting the latch 122 to engage the pin 133of the selector Wheel S As soon as the surge of current through each ofthe windings ceases the armatures of all of the polar magnets will swingto their neutral positions and release the escapements of the selectorwheels. The selector wheels S S and S, will at once be restored tonormal, but owing to the engage ment of the latch 122 vith the pin 182of the selector wheel S the latter will remain in its advanced positionuntil relay 118 releases its armature at the end of the long pulse,thereby discharging condenser 119 and cans ing a surge of currentthrough each of the polar magnets in the opposite direction, with theconsequent advance of each of the selectors one step. Selector wheel Swill now be advanced to its sixth position and the other three selectorwheels will be advanced but one step from normal. At the end of thesurge of current through the polar magnets, each of their armatures willswing to neutral position, thus releasing the escapements and permittingeach of the selector wheels to be restored to normal, the pins of noneof the selector wheels being engaged with the corresponding latches inthe positions to which the wheels were advanced at the end of the longpulse.

During the continuance of the long pulse, the latch 122, being engagedwith the pin 132 of the selector S the wiper 142 carried by said disccompleted the circuit of the relay 92 for a sufiicient length of time toenablex said relay to become energized. Upon the energization of relay92, a circuit is closed from ground, over its outer upper contact, overthe back contact of relay 159, and through the winding of relay 160 tobattery. Relay 160 attracts its armature and connects ground to aconductor leading to the lower outer contact of relay 92, whereby relay92 is locked up independently of the circuit closed by the selectorwheel 8,.

A circuit is also established by the relay too 160 from ground, over itsfront contact, over the normal contact of chain relay 165, and throughthe winding of chain relay 161 to battery. Chain relay 161 is thusenergized and the series of chain relays 161 to 165 are successivelyactuated. At the same time that the chain relay 164 closes the circuitof the chain relay 165, it also closes a circuit through the right-handwinding of relay 159. Relay 159, upon being energized. attractsitsarmature and shifts the ground connection previously maintained over theupper contact of relay 92 and through the winding of relay 160 to theleft-hand locking winding of relay 159. Relay 160 is accordinglyreleased and relay 159 also looked up by the relay 92. Relay 160, uponbeing released, opens the ground connection whereby relay 92 was lockedup, but before relay 160 has had an opportunity to be rc-- leased thechain relay 165 established a new locking ground for the relay 92 overthe front contact of said chain relay 165.

The actuation of relay 165 opens the normal make contact controlled bysaid relay, thereby opening the circuit of the first chain relay 161,which is accordingly released. The remaining relays of the chain at oncebeginto release in successive order until the last relay- 165 of thechain permits its armature to fall ofl". This finally removes groundfrom the locking circuit of the relay 92, which is accordingly released.The ringing current which was transmitted to the terminal line L overthe innercontacts of the relay 92 during the time that the latter wasmaintained locked up, now ceases. It will be observed that the durationof theringing interval coincides with the time that it required for thefive chain relays to be successively energized in regular order and thensuccessively deenergized in regular order. The deenergization of therelay 92 disconnects ground over itsu'pper outer contact, from theleft-hand locking winding of relay 159 so that the latter is accordinglydeenergized and the circuit is restored to normal.

A code combination transmitted from the distant station consisting offour short pulses and one long pulse will advance all of the selectorwheels nine steps. 'The se lector wheel S, will be latched in its advanced position to close the circuit of the relay 94, while the otherselector wheels will all be released during the continuance of the longpulse. At the endof the long pulse, each of the selector wheels areagain ad vanced one step andno latching operation occurring inconnection with any of the discseach of the discs will be returned tonormal. The relay 94, upon being energized, sets into operation thechain relays in a manner similar to that described in connection withrelay 94, thereby causing ringing current to be transmitted over theline L until the last chain relay of the series is released, whereuponthe ringing current ceases.

It will of course beobviousthat any carrier channel may be employed asthe signaling channel. However, it is advantageous to use for thesignaling channel the "channel which is usually set aside as theso-called pilot channel, i. e., the channel which is used in a mannerwell known in the art, to indicate the variation of the transmissionequivalent of the circuit. The same channel may obviously be used bothas a pilot channel and as a signal channel without any interference.

It will be obvious that the general principles herein disclosed may beembodied in many other organizations widely different from thoseillustrated without departing from the spirit of the invention asdefined in the following claims.

What is claimed is:

1. In a signaling system, a plurality of transmission circuits, arotatable cam shaft having a cam for each transmission circuit, each cambeing so formed as to transmit a signal characteristic of thecorresponding transmission circuit, signal storing apparatus associatedwith said circuits, and controlling cireuits interconnecting said cams,said signal storing apparatus and said transmission circuits, saidcontrolling cir cuits being so arranged that in response to signalssubstantially simultaneously incoming from a plurality of saidtransmission circuits said signals will bestoi'ed by said storingapparatus and the storing apparatus will control the cams tosuccessively transmit to a distant station signals characteristic of theseveral transmission circuits, and

means at the distant station individually responsive to the differentcharacteristic signals.

2. In asignaling system, a plurality of transmission circuits, signalstoring apparatus associated therewith comprising relays, one.corresponding to each circuit, means whereby said relays will be lockedup in response to signals incoming from the corresponding transinissioncircuit, a rotatable cam shaftliaving cams corresponding to eachtransmission circuit, each cam. being so formed as ,totransmit asignalehar acteristic ot' the corresponding transmission circuit, asecond group of relays. one cor responding to each transmission circuit.means whereby each relay of the second group controls a correspondingcam to transmit the signal characteristic of the cm'respendingtransmission circuit to a distant station, and circuits for said secondgroup of relays whereby the relays of the'second group may be controlledby the storing when one relay of the second group is actuated the otherrelays of the group will be prevented from actuation until the signalcontrolled by the actuated relay is transmitted by the correspondingcam, and signal responsive means at the distant station individuallyresponsive to the signals transmitted by the several cams.

3. In a signaling system. a plurality of trans1n""ion circuits, signalstoring apparatus associate-l therewith comprising relays, onecorresponding to .each circuit, means whereby said relays will be lockedup in response to signals incoming from the corresponding transmissioncircuit, a rotatable cam shaft having cams corresponding to eachtransmission circuit, each cam being so formed as to transmit a signalcharacteristic of the corresponding transmission circuit, a second groupof relays, one corresponding to each transmission circuit, means wherebyeach relay of the second group controls a corresponding cam to transmita signal characteristic of the corresponding transmission cirruit to adistant station, circuits for said second group of relays whereby therelays of the second group may be controlled by the storing relays, saidcircuits being so arranged that when one relay of the second group isactuated the other relays of the group will be prevented from actuationuntil the signal controlled by the actuated relay is transmitted by thecorresponding cam, corresponding transmission circuits at the distantstation, and selective apparatus associated with said transmissioncircuits at the distant station, said selective apparatus beingresponsive to the signals transmitted by the said cams for selectivelytransmitting signals to the corresponding transmission circuit.

4. In a signaling system, a carrier transmission line interconnectingtwo stations, a plurality of carrier channels at each terminal stat-ionarranged to intercommunicate over said carrier line at different carrierfrequencies, a rotatable cam shaft having cam corresponding to eachcarrier channel at one of said stations, said cams being so formed as totransmit signals characteristic of the corresponding channel, meansresponsive to a signal incoming to a carrier channel to set thecorresponding cam into operation to transmit its characteristic signal,a source of carrier current common to said carrier channels, means tosuperpose upon said carrier current the characteristic signals producedby said cams, means to transmit the signal superposed on said carriercurrent over said carrier line to the distant station, means at thedistant station to detect the signals thus transmitted, and selectiveapparatus at the distant station responsive to the detected signalstoimpress a signal upon the carrier channel at the distant stationcorresponding to the channel upon which the signal originated at saidfirst station.

5. In a signaling system, a carrier transmission line interconnectingtwo stations, a plurality of carrier channels at each termi nal stationarranged to intercoinmunicate over said carrier line at differentcarrier frequencies, a rotatable cam shaft having cams corresponding toeach carrier channel at one -of said stations, said cams being so formedas to transmit signals characteristic of the corresponding channel,means responsive to a signal incoming to a carrier channel to set thecorresponding cam into operation to transmit its characteristic signal,a source of carrier current common to said carrier channels, a source oflow frequency alternating current, means whereby said carrier currentmay be modulated by said low frequency current, means for impressing onsaid low frequency current the characteristic signals produced by saidcams, means to transmit the modulated carrier current over said carriercircuit, means at said distant station to detect the low frequencycurrent in accordance With which said carrier current is modulated,means to translate the detected current into characteristic signals, andselective apparatus at the distant station responsive to saidcharacteristic signals for selecting and transmitting a signal to thechannel at the distant station corresponding to the channel upon whichthe signal originated at said first station.

6. In a signaling system, a carrier transmission line interconnectingtWo stations, a plurality of carrier channels at each terminal stationarranged to intercommunicate 195 over said carrier line at differentcarrier frequencies, means for storing signals originating on saidcarrier channels, a rotatable cam shaft having cams thereoncorresponding individually to said channels, said cams being so formedas to transmit signals characteristic of the corresponding channel,circuits interconnecting said storing means and said cams whereby inresponse to a plurality of stored signalssaid cams Will operate tosuccessively transmit signals characteristic of the correspondingchannels, a source of carrier frequency common to said channels, meansto superpose on the carrier current from said source the signalstransmitted by said cams, means to trans mit the carrier current Withsignals superposed thereon over saidv carrier transmission line, meansat the distant station to detect the characteristic signals supenposedupon the carrier, and selective apparatus at the distant stationoperating in response to the detected characteristic signals to selectand apply a signal to the channel thereat corresponding to the channelupon which a corresponding signal originated at said first station.

7. In a signaling system, a carrier transmission line interconnectingtwo stations, a plurality of carrier channels at each termi- -nalstation. arranged to intercommunicate over said carrier line atdifferent carrier frequencies, means for storing signals originating onsaid carrier channels, a rotatable camshaft having cams thereoncorresponding individually to said channels, said cams being so formedas to transmit signals characteristic of the correspond ing channel,circuits interconnecting said storing means and said cams whereby inresponse to a plurality of stored signals said cams will operate tosuccessively transmit signals characteristic ofthe correspondingchannels, a source of low frequency alternating current, a source ofcarrier current, means to modulate said carrier current in accordancewith said low frequency current, means to impress upon said lowfrequency current the characteristic signals transmitted by said cams,means at the distant station to detect said low frequency alternatingcurrent, means to translate the detected low frequency alternatingcurrent into characteristic signals corresponding to those transmittedby said cams, and selective apparatus at said distant station responsiveto the translated characteristic signals to select and apply a signal tothe channel at said distant station corresponding to the channel onwhich the corresponding signal originated at said first station.

8. In a signaling system, a transmitting station and a receivingstation, a plurality of transmission circuits at each station, atransmission medium between said stations for interconnecting thetransmission circuits at the two stations, means to transmit from thetransmitting, station to the receiving station characteristic signalscorresponding to each of the transmission circuits of the transmittingstation, selective apparatus at the receiving station selectivelyresponsive to received characteristic signals, said selective apparatusresponding to a particular characteristic signal to select the corresponding transmission circuit at the receiving station and apply asignal thereto, and a timing arrangement set into operation by saidselective apparatus to determine the duration of the signal applied tothe trans mission circuit.

9. In a signaling system, a transmitting station and a receivingstation, a plurality of transmission circuits at each station, atransmission medium between said stations for interconnecting thetransmission cirthe transmitting station, selective apparatus at thereceivlng station selectivelyv responsive to recelved characteristicsignals,

.said selective apparatus responding to a particular characteristicsignal to select the corresponding transmission circuit at the receivingstation and apply a signal thereto, a timing arrangement set intooperation by said selective apparatus to determine the duration of thesignal. applied to the transmission circuit, and means whereby saidselective apparatus may'be restored to normal upon the application ofthe signal to the transmission circuit in order to selectively respondto a succeeding characteristic. signal while the preceding signal isbeing transmitted to its circuit.

10. In a signaling system, a carrier transmission line interconnectingtwo stations, a plurality of carrier channels at each terminal stationarranged to intercommunicate over said carrier line at different carrierfrequencies, a source of carrier current common to said channels at oneof said stations,

. means to impress upon the current from said source successive signalscharacteristic of the individual channel, means to transmit the carriercurrent with the signals impressed thereon to the distant station, meansat the distant station to successively detect from the transmittedcarrier current the successive characteristic signals originating atsaid first station, selective apparatus at said distant stationresponsive tothe detected characteristic signals, said selectiveapparatus responding to a given detected characteristic signal to selectand apply a signal to the channel corresponding to that upon which thesignal originated at said first station, and a timing arrangement setinto operation by said selective apparatus to determine the length oftime during which the signal will be applied.

ll. In a signaling system, a carrier transmission line interconnectingtwo stations, a plurality of carrier channels at each terminal stationarranged to intercommunicate over said carrier line at different carrierfrequencies, a source of carrier current common to said channels at oneof said stations, means to impress upon the current from said sourcesuccessive signals characteristic of the individual channels, means totransmit the carrier current with the signals impressed thereon to thedistant station, means at the distant station to successively detectfrom the transmitted carrier current the successive characteristicsignals originating at said first station, selective apparatus at saiddistant station responsive to the detected characteristic signals, saidselective apparatus responding to a given detected characteristic signalto select and apply a signal to the channel corresponding to that uponwhich the signal originated at said first station, a timing arrangementset into operation by said selective apparatus to determine the lengthof time during which the signal will be applied, and means to restoresaid selective apparatus to normal upon the application of a signal to agiven channel so that it may respond to the succeeding characteristicsignal during the continuance of the signal then being applied to one ofthe'channels.

12. In a signaling system, a *arrier transmission line interconnectingtwo stations, a plurality of carrier channels at each terminal stationarranged to intercommunicate over said carrier line at different carrierfrequencies, a source of carrier current common to said channels at oneof said stations, a source of low frequency alternating current, meansto modulate said carrier current in accordance with said low frequencycurrent, means to impress upon said low frequency alternating currentsuccessive characteristic signals corresponding to the several carrierchan nels, means to transmit the modulated carrier current over saidcarrier transmission circuit tothe distant station, means at the distantstation to detect from the received carrier current the low frequencycurrent in accordance with which it is modulated, means to translate thedetected low frequency current into successive characteristic signalscorresponding to the channels at said first station, selective apparatusat said distant station responsive to the translated characteristicsignals, said selective apparatus responding to a given translatedcharacteristic signal to select and apply a signal to a carriertransmission channel at said station corresponding to the carriertransmission channel at said first station upon which the signaloriginated, and timing apparatus set into operation by said selectiveapparatus to determine the length of time during'which the signal is tobe applied to the carrier transmission channel.

13. In a signaling system, a carrier transmission line interconnectingtwo stations, a plurality of carrier channels at each terminal stationarranged to intercommunicate over said carrier line at different carrierfrequencies, a source of carrier current common to said channels at oneof said stations, a source of low frequency alternating current, meansto modulate said carrier current in accordance with said low frequencycurrent, means to impress upon said low frequency alternating currentsuccessive characteristic signals corresponding to the several carrierchannels, means to transmit the modulated carrier current over saidcarrier transmission circuit to the distant station, means at thedistant station to detectfrom the received carrier current the, lowfrequency current in accordance with which it is modulated, means totranslate the detected low frequency current into successivecharacteristic signals corresponding to the channels at said firststation, selective apparatus at said distant station responsive to thetranslated characteristic signals, said selective apparatus respondingto a given translated characteristic signal to select and apply a signalto a carrier transmission channel at said station corresponding to thecarrier transmission channel at said first station upon which the signaloriginated, timing apparatus set into operation by said selectiveapparatus to determine the length of time during which the signal is tobe applied to the carrier transmission channel, and means to restoresaid selective apparatus to normal so that it may respond to asucceeding characteristic channel during the continuance of the signalthen being applied to one of the chan nels.

In testimony whereof, I have signed my name to this specification this14th day of May 1924.

RALPH K. BON ELL.

